:root {
  --bg: #f6f7f9;
  --surface: #ffffff;
  --text: #16202a;
  --muted: #5a6877;
  --line: #dde2e8;
  --accent: #0b5cad;
  --accent-text: #ffffff;
  --good: #137a45;
  --good-bg: #e3f4ea;
  --bad: #b3261e;
  --bad-bg: #fbe7e5;
  --focus: #f2a900;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #11161c;
    --surface: #1a222b;
    --text: #e8edf2;
    --muted: #9aa8b6;
    --line: #2d3946;
    --accent: #5aa7f0;
    --accent-text: #08121c;
    --good: #59c98c;
    --good-bg: #17382a;
    --bad: #f08a83;
    --bad-bg: #3d1f1d;
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.55 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  padding-inline: 16px;
}

a { color: var(--accent); }

.top {
  position: sticky;
  top: 0;
  z-index: 5;
  background: var(--bg);
  border-bottom: 1px solid var(--line);
  margin-inline: -16px;
  padding: 8px 16px 0;
}

.top-inner {
  max-width: 820px;
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 4px 16px;
}

.brand {
  font-weight: 700;
  font-size: 1.1rem;
  text-decoration: none;
  color: var(--text);
}
.brand span { color: var(--accent); }

.clock {
  font-variant-numeric: tabular-nums;
  font-size: 0.9rem;
  color: var(--muted);
}
.clock.running { color: var(--text); font-weight: 600; }
.clock.low { color: var(--bad); }

.tabs {
  max-width: 820px;
  margin: 6px auto 0;
  display: flex;
  gap: 4px;
}
.tabs a {
  flex: 1;
  text-align: center;
  padding: 8px 4px;
  text-decoration: none;
  color: var(--muted);
  border-bottom: 3px solid transparent;
  font-weight: 600;
  font-size: 0.95rem;
}
.tabs a.active { color: var(--accent); border-bottom-color: var(--accent); }

main {
  max-width: 820px;
  margin: 0 auto;
  padding-block: 20px 32px;
}

h1 { font-size: 1.5rem; margin: 0 0 4px; }
h2 { font-size: 1.15rem; margin: 24px 0 8px; }
.lead { color: var(--muted); margin: 0 0 16px; }

.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 16px;
  margin-bottom: 12px;
}

button, select {
  font: inherit;
  border-radius: 8px;
  border: 1px solid var(--line);
  background: var(--surface);
  color: var(--text);
  padding: 8px 14px;
  cursor: pointer;
}
button.primary {
  background: var(--accent);
  color: var(--accent-text);
  border-color: var(--accent);
  font-weight: 600;
}
button.good { border-color: var(--good); color: var(--good); font-weight: 600; }
button.bad { border-color: var(--bad); color: var(--bad); font-weight: 600; }
button:focus-visible, a:focus-visible, select:focus-visible, summary:focus-visible, input:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
}

.row { display: flex; flex-wrap: wrap; gap: 8px; align-items: center; }
.spread { justify-content: space-between; }

.steps { list-style: none; margin: 0; padding: 0; }
.steps li {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  padding: 12px 0;
  border-bottom: 1px solid var(--line);
}
.steps li:last-child { border-bottom: 0; }
.steps input { width: 20px; height: 20px; margin-top: 3px; flex: none; }
.steps .done .step-title { text-decoration: line-through; color: var(--muted); }
.step-title { font-weight: 600; }
.step-meta { color: var(--muted); font-size: 0.9rem; }

.tactics { margin: 0; padding-left: 20px; }
.tactics li { margin-bottom: 8px; }

.chips { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 16px; }
.chip {
  padding: 6px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  text-decoration: none;
  color: var(--text);
  background: var(--surface);
  font-size: 0.92rem;
}
.chip.active { background: var(--accent); color: var(--accent-text); border-color: var(--accent); }

details.sec {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 12px;
  margin-bottom: 10px;
  padding: 0 16px;
}
details.sec summary {
  cursor: pointer;
  font-weight: 700;
  padding: 12px 0;
}
details.sec ul { margin: 0 0 12px; padding-left: 20px; }
details.sec li { margin-bottom: 8px; }

.flash {
  min-height: 190px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  font-size: 1.2rem;
  cursor: pointer;
  user-select: none;
}
.flash .side { font-size: 0.8rem; color: var(--muted); text-transform: uppercase; letter-spacing: 0.06em; margin-bottom: 8px; }
.flash.back { border-color: var(--accent); }

.progress { height: 8px; border-radius: 4px; background: var(--line); overflow: hidden; margin: 8px 0 16px; }
.progress > div { height: 100%; background: var(--accent); }

.q-text { font-size: 1.1rem; font-weight: 600; margin: 0 0 12px; }
.opts { display: grid; gap: 8px; }
.opt {
  text-align: left;
  display: flex;
  gap: 10px;
  padding: 12px;
  width: 100%;
}
.opt .lbl { font-weight: 700; color: var(--muted); flex: none; }
.opt.correct { background: var(--good-bg); border-color: var(--good); }
.opt.wrong { background: var(--bad-bg); border-color: var(--bad); }
.explain { margin-top: 12px; padding: 10px 12px; border-left: 4px solid var(--accent); background: var(--bg); border-radius: 4px; }

.score { font-size: 2.2rem; font-weight: 800; margin: 0; }
.bars { display: grid; gap: 10px; margin: 12px 0; }
.bar-row { display: grid; grid-template-columns: minmax(0, 1fr) 56px; gap: 8px; align-items: center; }
.bar-name { font-size: 0.92rem; }
.wrong-item { padding: 10px 0; border-bottom: 1px solid var(--line); }
.wrong-item:last-child { border-bottom: 0; }
.muted { color: var(--muted); }

.foot {
  max-width: 820px;
  margin: 0 auto;
  padding-block: 16px 32px;
  color: var(--muted);
  font-size: 0.85rem;
  border-top: 1px solid var(--line);
}

@media (max-width: 480px) {
  .tabs a { font-size: 0.88rem; }
}